Funds are requested for the purchase of an analytical ultracentrifuge to enhance the research capabilities in physical biochemistry at Florida State University. The instrument will be housed in the Physical Biochemistry Facility, a centralized facility located in the Institute of Molecular Biophysics, that serves faculty, students, and postdoctoral associates in the Departments of Chemistry and Biochemistry, Biological Sciences, and Molecular Biophysics. This facility is staffed by a full-time research faculty member whose salary is paid for by the University, not by user fees, thereby providing substantial support for users. NIH funded projects that will be enhanced by this equipment include: metal activation of repressor proteins obtained from Corynebacterium diphtheriae, Mycobacterium tuberculosis, and Bacillus anthracis, the assembly of protein-RNA complexes comprising snoRNPs, structural biology of membrane proteins from Mycobacterium tuberculosis, characterizing the 3-D morphology of the native and ligand-bound conformation of the HIV-1 and SIV envelope (Env) surface (gp120) and transmembrane (gp41) glycoproteins, 3D structure and assembly of insect flight muscle, in characterizing the structure of cell adhesion complexes, and in characterizing the interaction of cell growth factors with heparan. In addition to these major projects, the centrifuge will potentially benefit the research of other faculty in the Institute of Molecular Biophysics and other departments participating in biomolecular research at Florida State University. The new instrumentation will enhance the research capability and productivity of our faculty and provide training opportunities for graduate students and postdoctoral associates in the Departments of Biology, Chemistry and Biochemistry, and Molecular Biophysics. Relevance: Analytical ultracentrifugation is a method used to characterize the size and shape of biological molecules in solution. This instrument will be used by the investigators to define the stoichiometry and energetics of assembly for biologically important macromolecular complexes involved in muscle contraction, RNA post-translational modification, transcriptional regulation, and membrane protein ion channels. [unreadable] [unreadable] [unreadable]